1. Field of the Invention
The present invention relates generally to communication systems and, more particularly, to providing an improved method for Global System for Mobile communication (GSM) network selection.
2. Description of the Related Art
Global System for Mobile communication (GSM) is one of the most widely used wireless access systems in today's fast growing communication infrastructure. As is well known, main components of a GSM network include a Mobile Station (MS or “mobile”), at least one Base Transceiver Station (BTS), a Base Station Controller (BSC), and a Mobile Switching Center (MSC). A MS consists of Mobile Equipment (ME) along with a Subscriber Identity Module (SIM). A SIM includes an International Mobile Subscriber Identity (IMSI), which is a unique identifier of a subscriber. A BTS is physical equipment, such as a radio tower, that enables a radio interface to communicate with a MS. Each BTS may serve more than one MS. The BSC manages radio resources, including a BTS, and may be connected to several BTSs. The BSC and BTS components, in combination, are generally referred to as a Base Station System (BSS). A MSC performs a switching function for the network, as well as registration, authentication, location updating, handovers, and call routing, among other functions.
A GSM network is made up of geographic areas. As shown in FIG. 1, these areas include cells 102, location areas (LAs) 104, MSC areas 106, and public land mobile network (PLMN) area 108. Cell 102 corresponds to an area served by one BTS. The GSM network identifies each cell via a cell global identity (CGI), which is broadcasted by each BTS. The CGI is made up of a Mobile Country Code (MCC), a Mobile Network Code (MNC), a Location Area Code (LAC), and a Cell Identity (CI). LA 104 typically encompasses a group of cells and is used, for example, to limit an area in which a subscriber is paged. Each LA is served by one or more BSCs, which are themselves controlled by a single MSC. MSC area 106 represents a part of a GSM network implementation that is covered by a single MSC. A MSC area typically consists of more than one LA. PLMN area 108 is an area served by one network operator. Individual PLMNs are identified by their MCC and MNC, where the MNC specifies a home PLMN network of a MS, or mobile.
In the mobile marketplace, there are geographical areas that are often covered by more than one GSM network service provider. Conventionally, when a mobile powers on, the mobile camps onto a cell in which it is currently located and listens for a CGI broadcasted by a BTS of the cell. The mobile then selects a network service provider based only on a MNC and MCC in the CGI. Since the conventional network selection process utilizes only a MCC and a MNC, the process is often incapable of properly selecting an appropriate network service provider, especially in geographical areas in which completing network service providers have overlapping coverage. In an area where there is coverage from a home operator and a competitor, a mobile recognizes both networks' MCC and MNC. However, if the home operator's signal level and/or quality is lower that the that of the competitor's, the mobile selects the competitor's network and may stay on it. This causes the home operator to incur roaming charges on behalf of the subscriber, thus resulting in a loss of revenue. Furthermore, a network service provider must rely on other service providers (i.e., competitors) to allow its subscriber to operate (and roam). The home network service provider does not have control over roaming of its subscribers.
In view of the foregoing, there is a need for an improved GSM selection process and related functionality.